1. Field of the Invention
The present invention relates to a technique for extracting an area of a document from an image read by an image reading apparatus such as a scanner.
2. Description of the Related Art
Heretofore, in document scanning, a user places a document such as a photograph on a document positioning plate and subjects an image read by a scanner on the whole surface of the document positioning plate to an edge extraction processing and a luminance and saturation determination processing to extract the edge of the document, creating the image data only of the area of the document. The position where the document is positioned and the tilt thereof are detected to extract the image of the document.
When the document is read by a scanner, however, an area around the edge of the document can be darkened by a shadow or brightened due to excessive reflected light. Normally, the document is obliquely irradiated with the light of the scanner, so that such shadow and excessive reflected light are generated. A method for removing the shadow has been discussed, but a method for correcting the excessive reflected light has not been proposed.